What does a shunt do?

• A. Diverts CSF away from lateral ventricles
• B. CSF is reabsorbed and excess excreted
• C. Increases CSF production
• D. Blocks CSF flow to the ventricles

Answer: (A)

The main concept here is how a shunt helps relieve hydrocephalus by redirecting CSF away from the brain's ventricular system. When CSF accumulates in the ventricles (often from obstruction or impaired absorption), it causes ventricles to enlarge and pressure to rise. A shunt provides a controlled drainage pathway, typically from the lateral ventricles to another body cavity (often the peritoneal cavity), so the excess CSF can be absorbed elsewhere. This reduces intracranial pressure and ventricular dilation.

This is different from normal physiology, where CSF is produced and then reabsorbed naturally; a shunt doesn’t increase production, nor does it enhance reabsorption on its own, and it doesn’t block CSF flow. It simply diverts it to relieve buildup.